Two recent studies published in the Journal of the American Medical Association (JAMA) showed that highly structured diet and exercise programs could produce sustained weight loss for up to two years. Both studies used pre-packaged meals along with regular exercise regimens, periodic counseling and financial incentives to achieve their results.

One of the studies used Jenny Craig weight-loss products. The second study facilitated dietary compliance with pre-packaged meal replacements (provided at no cost to participants) for most but not all meals.

Although commercial weight-loss programs are popular, there’s not much scientific evidence to draw conclusions from. A few studies suggest that some programs have the potential to result in weight loss equal to office-based counseling or medical interventions.

The authors of the JAMA studies suggest weight-loss regimens, including products such as Jenny Craig meal replacements, could be an alternative to popular surgical interventions, such as lap bands or gastric bypass procedures. But can the results be generalized to the average person?

Here’s the problem: Sustaining weight-loss programs outside of a clinical study setting may be cost-prohibitive.

In the Jenny Craig-based study, 442 overweight or obese women aged 18-69 were studied for more than two years. Study subjects received free, pre-packaged foods, in-person or telephonic counseling, and instructions for physical activity for 30 minutes a day, five days a week. Participants also received $25 for every follow-up visit to a clinic.

The average one-year weight loss was approximately 10%; the average two-year weight loss was about 7%. This degree of weight reduction has been shown in previous large studies to significantly reduce the risk of diabetes and cardiovascular disease. A control group that received counseling dropped only 2.1% body weight on average.

The second JAMA study evaluated 130 obese adult men and women for more than a year. They were randomly assigned to either a group that dieted and exercised throughout the year, or to a group with the same diet but whose exercise regimen was delayed by six months.

Exercise was more vigorous than in the first study, consisting of 60 minutes of exercise, five days per week, with a target of 10,000 steps per day. Like the first study, participants received regular dietary counseling, some free prepackaged meals and small financial incentives.

After six months, the group that started exercising right away lost more weight than the delayed exercise group. Exercisers lost an average of 24 pounds compared to 18 pounds in the control. By the end of the study, however, total weight loss was about the same in both groups. Both groups also had reduced waist circumference, lower blood pressure and insulin resistance, less visceral (internal organ) fat, and lower liver fat content.

So can we generalize the results of such programs to the rest of the overweight and obese population? First, the costs of such programs are quite high. For paying patients in the structured commercial program, enrollment fees for a year-long premium are $359 plus the cost of food. The cost of program-supplied food averages about $100 per week plus the cost of supplemental fruits, vegetables and dairy. Of course, these expenses would be offset by lower expenditure on a conventional diet.

Modest financial incentives and counseling costs plus exercise regimens add to the cost and complexity of such programs. So while free prepared meals and incentivized structured weight-loss programs may be effective, sustaining such programs outside of a clinical study setting may be challenging.

Considering the health consequences of obesity however, it may ultimately prove cost-effective to provide such expensive services to obese patients. That decision will be left up to the insurers, employers and the patients to decide.